A roll having controlled bending is known from DE 30 22 491 C2. This type of roll is suitable not only for calenders, but also for smoothing machines; presses; parts of paper, pulp, and pressure machines; or rolling mills for steel, plastic, and the like.
In conventional rolls, the support elements have a closed support surface with two pockets. Each of the pockets is situated opposite a cylindrical pressure chamber, which is connected to the associated pocket through a throttle bore, and which can be supplied, by means of a control device, with a controllable pressure. The two pressure chambers can be supplied with the same pressure or with different pressures. The support force that can be applied by the support element is limited by the dimensions of the support element and by the control range of the pressure.
In U.S. Pat. No. 3,587,152 to Hold, a roll is disclosed having controlled bending, in which ring elements are used as a ring seal, such that the annular pressure surface which faces the carder is acted upon by the pressure of the in-flowing pressure medium. In this way, the front surface of the ring element is pressed against the inside surface of the roll sleeve. The interior space enclosed by the ring element is connected by a throttle to the intake for the pressure medium. The pressure prevailing in the interior space acts on the roll sleeve. Here, too, the force that can be applied to the roll sleeve is limited by the dimensions of the ring element and by the control range of the pressure.
From DE 38 20 974 C2, a roll having controlled bending is known which has piston-shaped sealing elements, in which a frontal pocket, facing the roll sleeve, is connected unthrottled to a pressure chamber which is connected to the pressure feed line. This pocket is surrounded by a border containing border chambers. The latter are at a distance from one another in the circumferential direction and are connected, by a throttle, to a second pressure feed line. Furthermore, it is possible to completely fill the annular space between the roll sleeve and the carder with a pressure medium at a prescribed pressure. If the pressure in the pocket is higher than the pressure in the intermediate space, the result is an "over-pressure element"; if it is smaller, the result is an "under-pressure element".